Niacin Plus Statin to Prevent Vascular Events

BACKGROUND:

Coronary heart disease (CHD) remains the leading cause of death and disability in the Western world, with approximately 12.6 million individuals in the United States having a history of myocardial infarction (MI), angina, or both. There is mounting evidence that "conventional" therapies aimed at traditional risk factors have not optimized clinical outcomes. For example, in the Heart Protection Study with 20,536 subjects, the 5-year risk of a first major vascular event (nonfatal MI or CHD death, stroke, or coronary or noncoronary revascularization) among placebo-treated patients was 25%. Treatment with simvastatin reduced this risk to 20% over 5 years, which would project out to a 10-year risk of 40%. (The National Cholesterol Education Program Adult Treatment Panel III considers "high risk" or CHD equivalent a 10-year risk of an event greater than 20%.) Even among patients entering the study with baseline low density lipoprotein cholesterol (LDL-C) already near or at goal (i.e., LDL-C less than 116 mg/dL) and who achieved a mean on-trial LDL-C of 70 mg/dL with simvastatin, the 5-year risk of an event was still 18% (projecting to a 10-year risk of 36%). This residual and unacceptably high risk is likely due to the increasing prevalence of obesity, type II diabetes mellitus, and the metabolic syndrome. These disorders are typically accompanied by a constellation of abnormalities that include impaired glycemic control, hypertension, procoagulant and inflammatory states, and atherogenic dyslipidemia. The latter includes a wide spectrum of lipid abnormalities (low HDL-C, high triglycerides and triglyceride-rich remnant lipoproteins, and a preponderance of small dense, highly-oxidizable LDL particles).

Conventional LDL-C-focused therapies are not effective in targeting this type of dyslipidemia. Evidence that therapy directed at atherogenic dyslipidemia among patients with CHD can lower outcomes was shown with gemfibrozil in the VA-HIT trial, which showed a 22 to 24% cardiovascular (CV) event reduction by raising HDL-C (by an average of 6%) and lowering triglycerides (by an average of 31%). Niacin is an even more effective agent for simultaneously raising HDL-C and lowering triglycerides and levels of small dense LDL, and holds the most promise among existing therapies for substantial risk reduction in this population when added to a statin. This was demonstrated in the HDL Atherosclerosis Treatment Study (HATS) trial in which atherosclerosis progression was virtually halted and CV events were reduced by 60 to 90% using combined niacin plus statin therapy.

DESIGN NARRATIVE:

AIM-HIGH is a multicenter, randomized, double-blind, parallel-group, controlled clinical trial designed to test whether the drug combination of extended release niacin plus simvastatin is superior to simvastatin alone, at comparable levels of on-treatment LDL-C, for delaying the time to a first major CV disease outcome over a 4-year median follow-up in patients with atherogenic dyslipidemia. Prior clinical trials have found only 25 to 35% CV risk reduction using statin monotherapy (i.e., event rate 2/3 to 3/4 of placebo rate). The study is needed to confirm whether statin-niacin combination therapy, designed to target a wider spectrum of dyslipidemic factors in addition to LDL-C, will provide a more substantial (greater than 50%) reduction of CV events. Epidemiologic studies confirm the high prevalence of atherogenic dyslipidemia and its impact on CV event rates. Preliminary clinical trials suggest that targeting these factors with dyslipidemic therapy will reduce CV events. The study will enroll an estimated 3,300 men and women more than 45 years old at high risk of recurrent CV events by virtue of having established CV disease together with the two dyslipidemic elements of metabolic syndrome: low HDL-cholesterol (HDL-C) (less than or equal to 40 mg/dl) and high triglycerides (TG) (greater than or equal to 150 mg/dl). The study specifically aims to test this hypothesis for the primary composite clinical end point of CHD death, nonfatal MI, ischemic stroke, hospitalization for acute coronary syndrome with objective evidence of ischemia (troponin-positive or ST-segment deviation), or symptom-driven coronary or cerebral revascularization. Secondary end points include the composite of CHD death, nonfatal MI, ischemic stroke, or hospitalization for high-risk acute coronary syndrome; the composite of CHD death, nonfatal MI or ischemic stroke; and cardiovascular mortality.